Method of making window unit

ABSTRACT

A method of making a window unit is provided which may result in improved yields. In certain example embodiments, the method involves coating a substrate with both (i) a solar control/management coating, and (ii) a protective layer (e.g., of or including diamond-like carbon (DLC)) over the solar control/management coating. The protective layer protects the coated substrate from scratches and/or the like during processing prior to heat treatment. Then, during heat treatment, the protective layer(s) is burned off in part or in whole. Following heat treatment, the coated article (substrate with solar control/management coating thereon) is coupled to another substrate in order to form the window unit.

This application is a divisional of application Ser. No. 10/073,266,filed Feb. 13, 2002, now abandoned, the entire content of which ishereby incorporated herein by reference in this application.

This invention relates to a method of making a window unit (e.g., IGwindow unit). More particularly, this invention relates to a method ofmaking a window unit in which a temporary protective layer (e.g., of orincluding diamond-like carbon (DLC)) is provided over a solar controlcoating so that the coated article can be protected from scratches orthe like during processing, with the temporary protective layersubsequently being burned off during heat treatment (e.g., thermaltempering or heat bending) prior to use of the final resulting product.

BACKGROUND OF THE INVENTION

Insulating glass (IG) window units typically include first and secondglass substrates spaced apart from one another via at least one spacerso as to define a gap therebetween. For example, see U.S. Pat. No.5,557,462. The gap between the glass substrates may or may not beevacuated and/or filled with gas in different instances. As in the '462patent, one of the glass substrates of the IG window unit is oftencoated with a solar control/management coating (e.g., a low-E coating).Solar control/management coatings typically include at least one layer(e.g., of or including Ag, Au, NiCr, and/or the like) that reflectsinfrared (IR) and/or ultraviolet (UV) radiation. Example solarcontrol/management coatings may be found, for example and withoutlimitation, in any of U.S. Pat. Nos. 3,682,528; 4,898,790; 5,376,455;5,377,045; 5,514,476; 5,557,462; 5,688,585; 5,770,321; 5,902,505;5,942,338; 6,059,909; 6,060,178; 6,132,881; or U.S. Pat. No. 6,159,607.

IG window units are typically made in the following manner. A firstglass substrate is coated (e.g., via sputtering or the like) with asolar control/management coating, and processed as follows. The coatedglass substrate may be shipped (e.g., via truck, train, ship, plane, orthe like) from the coating facility to an IG manufacturing facility, andput in inventory using a forklift or the like. Subsequently, a forkliftmay move the coated substrate from its inventory location to a cut-downline where the coated substrate is cut to size. The cut coated substratemay then be seamed, washed, and heat treated (e.g., thermally tempered).Thereafter, the coated substrate is coupled to another glass substratevia at least one spacer so as to form an IG window unit.

Unfortunately, during the course of such processing between coating andheat treatment, the coated substrate is moved on numerous occasions andis subject to damage (e.g., scratching). Low-E coatings are often softand tend to be prone to damage in this regard such as scratching. Yieldshave been found to suffer due to coated substrates which are damaged(e.g., scratched or otherwise rendered non-useable) between coating andheat treatment.

In view of the above, it will be appreciated by those skilled in the artthat there exists a need in the art for an improved method of makingwindow units (e.g., IG units, vehicle windshields, and/or the like)which include at least one coated substrate.

BRIEF SUMMARY OF THE INVENTION

An object of this invention is to provide an improved method of makinginsulating glass (IG) window units.

Another object of this invention is to provide an improved method ofmaking vehicle windshields. The method is also applicable to other typesof windows, monolithic and/or laminated.

Another object of this invention is to provide a method of making awindow unit (e.g., IG unit and/or vehicle windshield) which results inimproved yields. In certain example embodiments of this invention, themethod involves coating a substrate with both (i) a solarcontrol/management coating, and (ii) at least one protective layer(e.g., of or including diamond-like carbon (DLC)) over the solarcontrol/management coating. The protective layer(s) protects the coatedsubstrate from scratches and/or the like during processing prior to heattreatment (HT). Then, during heat treatment, the protective layer(s) isburned off in part or in whole. Following heat treatment, the coatedarticle (substrate with solar control/management coating thereon) iscoupled to another substrate in order to form the window unit.

Another object of this invention is to fulfill one or more of theabove-listed objects and/or needs.

Certain example embodiments of this invention fulfill one or more of theabove-listed objects and/or needs by providing a method of making awindow unit, the method comprising: providing a solar control coating ona glass substrate; depositing a temporary protective layer on the glasssubstrate over the coating, the temporary protective layer having anaverage hardness of at least 10 GPa; heat treating the substrate withthe coating and protective layer thereon at a temperature of at least570 degrees C. so that the protective layer burns off; and followingsaid heat treating, coupling the glass substrate with the coatingthereon to another substrate in order to form the window unit.

Other example embodiments of this invention fulfill one or more of theabove-listed objects and/or needs by providing a method of making awindow unit, the method comprising: providing a coating on a glasssubstrate, the coating including at least one layer comprising Ag;depositing a protective layer comprising diamond-like carbon (DLC) onthe substrate over the coating; heat treating the substrate with thecoating and protective layer thereon so that the protective layercomprising diamond-like carbon (DLC) at least partially burns off duringthe heat treating; and following said heat treating, coupling the glasssubstrate with the coating thereon to another substrate in order to formthe window unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an IG window unit according to anexample embodiment of this invention.

FIG. 2 is a cross sectional view of a vehicle windshield according to anexample embodiment of this invention.

FIGS. 3( a), 3(b), 3(c) and 3(d) are cross sectional views progressivelyillustrating how a window unit is made according to an exampleembodiment of this invention.

FIG. 4 is a flowchart illustrating steps showing how a window unit ismade according to an example embodiment of this invention.

FIG. 5 is a cross sectional view of a coated substrate at a point intime during the manufacturing process according to an example embodimentof this invention, at which point in time the substrate is coated withboth a solar control coating and a temporary protective layer(s) (theprecise illustrated coating is provided for purposes of example only).

FIG. 6 is a cross sectional view of a coated substrate at a point intime during the manufacturing process according to another exampleembodiment of this invention, at which point in time the substrate iscoated with both a solar control coating and a temporary protectivelayer(s) (this precise illustrated coating is provided for purposes ofexample only).

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals refer to like parts/layers throughout theseveral views. The instant invention relates to methods of making windowunits including but not limited to insulating glass (IG) window unitsand vehicle windshields. Initially, before describing methods accordingto example embodiments of the instant invention, reference is made toFIGS. 1-2 which illustrate example window units which may be madeaccording to different example embodiments of this invention.

FIG. 1 is a cross sectional view of an insulating glass (IG) window unitwhich may be made in certain example embodiments of this invention. TheIG window unit includes first glass substrate 1 and second glasssubstrate 2 which are spaced apart from one another by one or morespacers 4. Each of substrates 1 and 2 is from about 1.0 to 10.0 mmthick, more preferably from about 1.8 mm to 4 mm thick. Spacer(s) 4 maybe provided around the edge/periphery of the window unit as inconventional IG window units, or alternatively may be provided in anarray throughout the viewing area of the window unit as in vacuum IGwindow units. Spacer(s) 4 function to space the substrates 1 and 2 fromone another so as to define space 6 therebetween. Space 6 may be atatmospheric pressure or lower in different embodiments of thisinvention, and may or may not be filled with gas. While substrates 1 and2 are of glass in preferred embodiments of this invention, they may beof other materials such as plastic in alternative embodiments of theinvention. The IG window unit of FIG. 1 has a visible transmission of atleast about 30% in certain example embodiments of this invention, morepreferably at least about 60%, and most preferably at least about 70%.

FIG. 2 is a cross sectional view of a vehicle windshield which may bemade in certain example embodiments of this invention. The windshieldincludes first glass substrate 1 and second glass substrate 2 that arelaminated together via a polymer inclusive interlayer 8. Interlayer 8may be of or include polyvinyl butyral (PVB), polyvinyl chloride,polypropylene, polyethylene, polyurethane, or any other suitablelaminating material. The windshield of FIG. 2 preferably has a visibletransmission of at least 70%, more preferably of at least 75%.

Still referring to FIGS. 1-2, each of these window units includes atleast one solar control/management coating 27 for reflecting certainamounts of infrared (IR) and/or ultraviolet (UV) radiation. Whilecoating 27 is provided on the interior surface of substrate 1 in FIGS.1-2, the coating 27 may instead be provided on the interior surface ofthe other substrate 2 in alternative embodiments of this invention.Moreover, in other embodiments of this invention it is possible toprovide a solar control/management coating 27 on each of substrates 1-2.Coating 27 may include one or more layers in different embodiments ofthis invention, although a multi-layered coating 27 is preferred.

The phrases “solar control coating” and “solar management coating”herein mean that the coating includes at least one layer of a material(e.g., Ag, Au, and/or NiCr) that functions to reflect certain amounts ofUV and/or IR radiation. Example solar control coatings 27 are shown inFIGS. 5-6. Moreover, solar control coating 27 may comprise any of thecoatings described and/or illustrated in any of U.S. Pat. Nos.3,682,528; 4,898,790; 5,376,455; 5,377,045; 5,514,476; 5,557,462;5,688,585; 5,770,321; 5,902,505; 5,942,338; 6,059,909; 6,060,178;6,132,881; or U.S. Pat. No 6,159,607, or may comprise any other suitablesolar control coating.

FIGS. 3-4 illustrate a method of making a window unit (e.g., IG unit orwindshield) according to an example embodiment of this invention. Inthis regard, for purposes of example, a process for making an IG windowunit according to an example embodiment of this invention will now bedescribed.

As shown in FIG. 3( a), a first glass substrate 1 (e.g.,soda-lime-silica glass, borosilicate glass, or any other suitable typeof glass) is coated with a solar control/management coating 27 (see stepA in FIG. 4). Coating 27 may be deposited on substrate 1 via sputteringor any other suitable technique. Thereafter, as shown in FIG. 3( b), atleast one temporary protective layer 29 is deposited on the substrate 1over solar control/management coating 27 (see step B in FIG. 4).Protective layer(s) 29 may or may not directly contact coating 27 indifferent embodiments of this invention (i.e., other layer(s) may beprovided between coating 27 and layer 29). Layer 29 may be from about 5to 3,000 Å thick in certain example embodiments of this invention, morepreferably from about 10-1,000 Å thick, and most preferably from about25 to 200 Å thick.

In certain example embodiments of this invention, temporary protectivelayer(s) 29 is of or includes diamond-like carbon (DLC). The DLCinclusive layer(s) 29 may be deposited on substrate 1 over coating 27using an ion beam source, or any other suitable technique. For example,any of the DLC layer(s) (and corresponding deposition techniques)disclosed in any of U.S. Pat. Nos. 6,335,086, 6,261,693, 6,303,225,6,303,226, 5,635,245, 5,527,596, or U.S. Pat. No. 5,508,092 (all herebyincorporated herein by reference) may be used to form layer(s) 29.Alternatively, any other suitable type of DLC may be used in layer(s) 29in other embodiments of this invention. Temporary protective layer(s) 29may include one or more layers in different embodiments of thisinvention. While protective layer 29 preferably comprises DLC in certainembodiments of this invention, this invention is not so limited; inparticular, layer 29 may be of or include any other suitable materialthat is capable of protecting coating 27 from scratching and can atleast partially burn off during heat treatment.

After substrate 1 has been coated with both solar control coating 27 andDLC layer(s) 29 (see FIG. 3( b)), the coated article may be processed(e.g., shipped, moved, cut, cleaned, seamed washed, and/or the like)(see step C in FIG. 4). As shown in FIG. 3( c), the coated article isthen subjected to heat treatment (e.g., thermal tempering; heat bending,and/or heat strengthening); and during this heat treatment the DLClayer(s) 29 burns off either in part or entirely (see step D in FIG. 4)(it is noted that the DLC may tend to burn off at a temperature of about400 degrees C.). Such heat treatment may, in certain example embodimentsof this invention, involve heating the coated substrate totemperature(s) of at least about 570 degrees C.; more preferably from1100° F. (593° C.) up to 1450° F. (788° C.) (more preferably from about1100 to 1200 degrees F., and most preferably from 1150-1200 degrees F.)for a sufficient period of time (e.g., at least 1 minute, morepreferably at least 5 minutes) to achieve the end result (e.g.,tempering, bending, layer 29 burn-off, and/or heat strengthening). FIG.3( c) illustrates that after this heat treatment, much or all of the DLCinclusive layer 29 is no longer present on the coated article since ithas burned off during the heat treatment.

After heat treatment (and thus after the DLC layer 29 has at leastpartially burned off), the coated substrate (i.e., substrate 1 with thesolar control coating 27 thereon) is coupled to another substrate 2 inorder to form the resulting window unit (see step E in FIG. 4). Exampleresulting window units are shown in FIGS. 1, 2 and 3(d).

As will be explained below, DLC is hard and serves to protect thecoating 27 from scratches and the like during the processing periodbetween the coating and heat treating stages of the manufacturingprocess. However, addition of the DLC layer(s) 29 to the coated articletends to reduce the visible transmission of the article. Thus, accordingto certain embodiments of this invention, the DLC layer(s) 29 is usefulfor protection purposes during the manufacturing process (its reductionin visible transmission is irrelevant during production), and it can beremoved (e.g., burned off) during heat treatment. It will be appreciatedthat the visible transmission of the coated article increases when theDLC layer(s) 29 is burned off, prior to formation of the final windowunit.

In certain example embodiments of this invention, when DLC for exampleis provided in temporary protective layer(s) 29, the layer(s) 29includes has an average hardness of at least about 10 GPa, morepreferably at least about 20 GPa, and most preferably from about 20-90GPa. Such hardness renders layer (s) 29 resistant to scratching, certainsolvents, and/or the like. Layer 29 may, in certain example embodimentswhere DLC is used, include more sp³ carbon-carbon (C—C) bonds than sp²carbon-carbon (C—C) bonds. In certain example embodiments at least about50% of the carbon-carbon bonds in the layer 29 may be sp³ carbon-carbon(C—C) bonds, more preferably at least about 60% of the carbon-carbonbonds in the layer 29 may be sp³ carbon-carbon (C—C) bonds, and mostpreferably at least about 70% of the carbon-carbon bonds in the layer 29may be sp³ carbon-carbon (C—C) bonds. In such embodiments, the DLC maybe a special type of DLC known as highly tetrahedral amorphous carbon(ta-C) (which may or may not be hydrogenated or otherwise doped) (e.g.,see U.S. Pat. No. 6,261,693, which is incorporated herein by reference).In certain example embodiments of this invention, the DLC may have adensity of at least about 2.4 gm/cm³, more preferably of at least about2.7 gm/cm³. Example linear ion beam sources that may be used to depositDLC inclusive layer 29 on substrate 1 include any of those in any ofU.S. Pat. Nos. 6,261,693, 6,002,208, 6,335,086, or U.S. Pat. No.6,303,225 (all incorporated herein by reference). When using an ion beamsource to deposit layer(s) 29, hydrocarbon feedstock gas(es) (e.g.,C₂H₂), HMDSO, or any other suitable gas, may be used in the ion beamsource in order to cause the source to emit an ion beam toward substrate1 for forming layer(s) 29 over coating 27. It is noted that the hardnessand/or density of layer(s) 29 may be adjusted by varying the ion energyof the depositing apparatus.

As discussed above, any suitable type of solar control coating 27 may beused in different embodiments of this invention. For purposes ofexample, and without limitation, two example solar control coatings 27are illustrated in FIGS. 5-6. Each of FIGS. 5 and 6 shows an examplesolar control coating 27 provided on a substrate between the substrate 1and the DLC inclusive temporary protective layer 29 (i.e., at the FIG.3( b) stage of the manufacturing process).

The example solar control coating 27 according to the FIG. 5 embodimentincludes first dielectric layer 3, second dielectric layer 5, firstlower contact layer 7 (which contacts layer 9), first conductivemetallic infrared (IR) reflecting layer 9, first upper contact layer 11(which contacts layer 9), third dielectric layer 13 (which may bedeposited in one or multiple steps in different embodiments of thisinvention), fourth dielectric layer 15, second lower contact layer 17(which contacts layer 19), second conductive metallic IR reflectinglayer 19, second upper contact layer 21 (which contacts layer 19), fifthdielectric layer 23, and finally sixth protective dielectric layer 25.The “contact” layers each contact at least one IR reflecting layer. Theaforesaid layers make up heat treatable low-E (i.e., low emissivity)coating 27 which is provided on substrate 1. The coating 27 ispreferably deposited on substrate 1 via sputtering, although otherdeposition techniques may also be used.

In certain examples embodiments, the coating 27 according to the FIG. 5embodiment may be as in the Table 1 below.

TABLE 1 (Example Materials/Thicknesses; FIG. 5 Embodiment) PreferredMore Example Layer Range ({acute over (Å)}) Preferred ({acute over (Å)})(Å) TiO₂ (layer 3) 0-400 {acute over (Å)} 50-250 {acute over (Å)} 100 ÅSi_(x)N_(y) (layer 0-400 {acute over (Å)} 50-250 {acute over (Å)} 170 ÅNiCrO_(x) (layer 7) 5-100 {acute over (Å)} 10-50 {acute over (Å)} 18 ÅAg (layer 9) 50-250 {acute over (Å)} 80-120 {acute over (Å)} 105 ÅNiCrO_(x) (layer 11) 5-100 {acute over (Å)} 10-50 {acute over (Å)} 16 ÅSnO₂ (layer 13) 0-800 Å 500-850 Å 650 Å Si_(x)N_(y) (layer 15) 0-800{acute over (Å)} 50-250 {acute over (Å)} 170 Å NiCrO_(x) (layer 17)5-100 {acute over (Å)} 10-50 {acute over (Å)} 18 Å Ag (layer 19) 50-250{acute over (Å)} 80-120 {acute over (Å)} 105 Å NiCrO_(x) (layer 21)5-100 {acute over (Å)} 10-50 {acute over (Å)} 16 Å SnO₂ (layer 23) 0-500Å 100-300 Å 150 Å Si₃N₄ (layer 25) 0-500 {acute over (Å)} 100-300 {acuteover (Å)} 250 Å

FIG. 6 illustrates a low-E heat treatable coating 27 according toanother embodiment of this invention. The FIG. 6 coating 27 is the sameas the FIG. 5 coating described above, except that either (i) dielectriclayer 3 is removed, or (ii) layers 3 and 5 are replaced with a singlesilicon nitride layer 40. Silicon nitride layer 40 may be of or includeSi₃N₄ in certain embodiments of this invention. In other embodiments,silicon nitride layer 40 may be of or include Si_(x)N_(y) where x/y maybe from about 0.65 to 0.80, or alternatively from about 0.76 to 1.5 insilicon rich embodiments. Additional details regarding the coatings 27of FIGS. 5-6, including example sputter process parameters for formingthe coatings, may be found in U.S. patent application Ser. No.09/794,224 (hereby incorporated herein by reference).

In certain exemplary embodiments of this invention, solar controlcoatings 27 may have one or more of the following characteristicsbefore/after heat treatment (HT) when in monolithic form, as set forthin Table 2:

TABLE 2 Coating 27 Monolithic Before/After Heat Treatment (HT)Characteristic General More Preferred Most Preferred R_(s)(ohms/sq.)(before HT): <=40.0 <=20.0 <=8.0 R_(s) (ohms/sq.)(after HT):<=40.0 <=20.0 <=8.0 E_(n) (before HT): <=0.30 <=0.20 <=0.08 E_(n) (afterHT): <=0.30 <=0.20 <=0.08

The example coatings 27 are provided for purposes of example and withoutlimitations. Other suitable solar control coatings may instead be usedin other embodiments of this invention. With regard to FIGS. 5-6, it isnoted that each of these coatings 27 includes a pair of metallic silver(Ag) layers 9, 19 which function to reflect IR and UV radiation, inorder to achieve low-E characteristics.

In certain embodiments of this invention, it is noted that other layers(e.g., a tie layer or the like) may be provided between the DLCinclusive layer 29 and coating 27. Such a layer(s) may or may not burnoff along with layer 29 during heat treatment.

While the temporary layer 29 comprises DLC in many embodiments discussedabove, certain embodiments of this invention are not so limited. Forexample, protective paint may be used instead of DLC for layer 29 incertain embodiments of this invention, can be burned off in a similarmanner.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A method of making a window unit, the method comprising: having acoated article comprising a coating on a glass substrate, the coatingincluding at least one layer comprising Ag, an uppermost layer of thecoating comprises silicon nitride, an ion beam deposited protectivelayer comprising diamond-like carbon (DLC) on the glass substrate overthe coating directly contacting the coating so that the protective layercomprising DLC directly contacts the uppermost layer of the coating thatcomprises silicon nitride; heat treating the glass substrate with thecoating and protective layer thereon so that the protective layercomprising diamond-like carbon (DLC) only partially burns off during theheat treating, so that following said heating treating part of the layercomprising DLC remains on the glass substrate.
 2. The method of claim 1,wherein said heat treating comprises heating the glass substrate to atemperature of at least about 570° C.
 3. The method of claim 1, whereinsaid heat treating comprises heating the glass substrate to atemperature of from about 590° C. to 788° C. for at least one minute inthermally tempering and/or heat bending the glass substrate.
 4. Themethod of claim 1, wherein the protective layer comprising DLC has anaverage hardness of at least about 10 GPa.
 5. The method of claim 1,wherein the protective layer comprising DLC has an average hardness ofat least about 20 GPa.
 6. The method of claim 1, wherein the protectivelayer comprising DLC includes more sp³ carbon-carbon bonds than sp²carbon-carbon bonds.
 7. The method of claim 1, wherein the coatingcomprises a second layer comprising Ag, and wherein the two layerscomprising Ag in the coating are spaced from one another with at leastone dielectric layer provided therebetween.
 8. The method of claim 7,wherein the dielectric layer comprises at least one of tin oxide andsilicon nitride.